Mapping uncertainty in managed aquifer recharge potential across unconfined and confined aquifers of the Murray-Darling Basin

The global decline in groundwater levels, particularly in agricultural regions, underscores the imperative for sustainable management practices augmented through Managed Aquifer Recharge (MAR). This study evaluated the potential for MAR in Australia’s Murray-Darling Basin (MDB), identifying substantial areas conducive to recharge across various regions experiencing long-term groundwater decline. Novel methods were developed to quantitatively assess potential recharge in unconfined and confined aquifers based on aquifer properties and account for uncertainty presenting a contrast to deterministic, weight-based spatial multi-criteria analyses. This investigation revealed that specific areas, including the Lower Namoi Alluvium and Goulburn-Murray Sedimentary Plain, exhibit higher recharge potential with 5-20 ML/ha feasible in unconfined aquifer systems at high confidence. Furthermore, this study found extensive areas at high confidence where the injection potential in confined aquifers ranged from 2.5-20 ML/d. The findings suggest that resource units characterized by high potential recharge areas and elevated resource stress values may benefit from MAR implementation, thereby mitigating stress and supporting more sustainable use. The economic viability of MAR is contingent upon various factors highlighting the need for tailored project design and site-specific assessments to ensure successful implementation. These results have significant implications for informing MAR implementation and future management strategies in the MDB.